The present invention relates to a novel substituted polyacetylene copolymer or, more particularly, to a film-forming substituted polyacetylene copolymer having a remarkably large permeability to oxygen gas.
It is well known that organosilicon polymers in general have a relatively large gas permeability coefficient as a polymeric material. For example, organopolysiloxanes, i.e. silicones, have an oxygen permeability coefficient as large as about 3.5.times.10.sup.-10 cm.sup.3 (STP).multidot.cm/cm.sup.2 .multidot.sec.multidot.cmHg. Silicone polymers are, however, not satisfactory as an oxygen permeable polymeric material due to the low mechanical strength thereof which is a limiting factor against decrease of the thickness of the films shaped thereof.
Various kinds of copolymers based on an organopolysiloxane have been proposed with an object to improve the mechanical strength of silicone including, for example, copolymers of an organopolysiloxane with polycarbonate, polystyrene and others. The increased mechanical strength in these copolymeric materials is, however, obtained only with sacrifice of the oxygen permeability coefficient so that oxygen permeable elements made of these copolymers are usually prepared with inconveniences by supporting an extremely thin membrane of the copolymer on a porous carrier film having a sufficient mechanical strength. Further, poly(vinyl trimethyl silane) resins have an oxygen permeability coefficient of about 4.5.times.10.sup.-9 in the same unit as above and attempts have been made to prepare an oxygen permeable element by supporting a membrane thereof on a porous supporting film or by shaping the resin into a self-supporting thin film although no attempts have been fully successful because the resins of this type hardly have a degree of polymerization sufficiently large to impart the films shaped thereof with a satisfactorily high mechanical strength.
On the other hand, it is reported in Polymer Preprints, volume 32 (10), page 2981 (1983) that a poly(1-trimethylsilyl-1-propyne) composed of the recurring monomeric units of the formula --C(Me).dbd.C(--SiMe.sub.3)--, in which Me is a methyl group, and prepared by the method described in Polymer Preprints, volume 31 (6), page 1189 (1982), Polymer Preprints, volume 32 (2), page 181 (1983), ibid. (6), page 1171 and ibid. (6), page 1175 has a very large gas permeability. This polymer has an oxygen permeability coefficient as large as 7.5.times.10.sup.-7 in the same unit as above but the separation factor, i.e. the ratio of the permeability coefficients, thereof between oxygen and nitrogen is about 1.5. Although the mechanical strength of this polymer is considerably large and sufficiently thin films can be shaped thereof, the above mentioned separation factor between oxygen and nitrogen is too small to be satisfactory for the application of the polymer film when it is used as such for the separation or enrichment of oxygen from or in air.